A study of the laxative action of wheat bran.

Abstract

The physiological action of wheat bran and a number of products isolated from bran was studied on dogs, which received as a basal ration a “synthetic” diet of casein, sucrose, and lard, together with the necessary mineral salts and vitamins. The purpose of the investigation was to determine what constituents of bran are responsible for its laxative effect. After a control period of 8 days the dogs were given the basal ration, supplemented with the bran or other material, the laxative power of which was to be determined. The frequency of defecation and the total weight of air-dried feces per eight-day period served as criteria of laxation.

Washed bran (starch-free) was laxative when ingested in amounts ranging from 10 per cent to 0.5 per cent by weight of the food intake. The average minimum effective dose was about 2 per cent (200 to 275 milligrams per kilo, body weight). About two grams of additional water was excreted in the feces for every gram of bran eaten.

The crude fiber of bran was a much more potent laxative than bran itself. The fiber when fed in such small daily doses as 0.5 gram to dogs weighing 7 to 9 kilos caused a marked rise in the number of defecations per eight-day period and produced an increase in the fecal output equal on the average to three times and, in some instances, to five or six times the weight of the ingested fiber. In general, bran itself did not possess this fecesforming power. Extensive experiments on 10 animals indicate that the laxative action of wheat bran is due at least in part to its crude fiber content.

The laxative factor of bran was not removed by acid and alkali hydrolysis or by prolonged, successive treatment with water, sodium chloride solution, hot 70 per cent alcohol, and weak sodium hydroxide solution.